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java.lang.Object EDU.oswego.cs.dl.util.concurrent.Latch
public class Latch
A latch is a boolean condition that is set at most once, ever. Once a single release is issued, all acquires will pass.
Sample usage. Here are a set of classes that use a latch as a start signal for a group of worker threads that are created and started beforehand, and then later enabled.
class Worker implements Runnable { private final Latch startSignal; Worker(Latch l) { startSignal = l; } public void run() { startSignal.acquire(); doWork(); } void doWork() { ... } } class Driver { // ... void main() { Latch go = new Latch(); for (int i = 0; i < N; ++i) // make threads new Thread(new Worker(go)).start(); doSomethingElse(); // don't let run yet go.release(); // let all threads proceed } }[ Introduction to this package. ]
Field Summary | |
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protected boolean |
latched_
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Fields inherited from interface EDU.oswego.cs.dl.util.concurrent.Sync |
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ONE_CENTURY, ONE_DAY, ONE_HOUR, ONE_MINUTE, ONE_SECOND, ONE_WEEK, ONE_YEAR |
Constructor Summary | |
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Latch()
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Method Summary | |
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void |
acquire()
Wait (possibly forever) until successful passage. |
boolean |
attempt(long msecs)
Wait at most msecs to pass; report whether passed. |
void |
release()
Enable all current and future acquires to pass |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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protected boolean latched_
Constructor Detail |
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public Latch()
Method Detail |
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public void acquire() throws java.lang.InterruptedException
Sync
acquire
in interface Sync
java.lang.InterruptedException
public boolean attempt(long msecs) throws java.lang.InterruptedException
Sync
The method has best-effort semantics: The msecs bound cannot be guaranteed to be a precise upper bound on wait time in Java. Implementations generally can only attempt to return as soon as possible after the specified bound. Also, timers in Java do not stop during garbage collection, so timeouts can occur just because a GC intervened. So, msecs arguments should be used in a coarse-grained manner. Further, implementations cannot always guarantee that this method will return at all without blocking indefinitely when used in unintended ways. For example, deadlocks may be encountered when called in an unintended context.
attempt
in interface Sync
msecs
- the number of milleseconds to wait.
An argument less than or equal to zero means not to wait at all.
However, this may still require
access to a synchronization lock, which can impose unbounded
delay if there is a lot of contention among threads.
java.lang.InterruptedException
public void release()
release
in interface Sync
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